ok4450- What’s the latest? Any luck?
Sorry I haven’t been back to this lately. Had intended to put it back together over the labor day weekend but I have 3 grown children who all own cars. Two of them were visiting and as per the usual, it fell upon me to catch some of their maintenance up instead.
The suction thing still baffles me though. With the throttle plate open the engine will suck my hand down pretty hard when it’s cranked over. It does not suck so hard at the end of the intake tract where it connects to the fuel distributor boot. (where the air sensor plate is located)
Logic dictates there must be a leak in that tract but the entire shebang is off right now and there’s not a hint of anything wrong with it. Even completely blocking that vacuum solenoid off on the radiator support doesn’t change anything.
I’ll slap this thing back together some evening this week and report back; probably with the same old, same old.
OK:
Let me see if I understand your last post. It looks like you’re saying:
1: If you remove the “sensor plate housing” away from the throttle plate area, that there is a strong vacuum at the throttle plate opening.
2: However, if you reconnect the “sensor plate housing” and check for vacuum at an upstream point (like near the air filter) then the vacuum isn’t as strong?
Did I understand your wording correctly?
Also, when you refer to the “warmup regulator”, are you referring to the Axillary Air Regulator?
Not quite. The air sensor plate doesn’t have anything to do with the vacuum; that’s the job of the throttle plate/throttle body.
This pic (not my car) is pretty fuzzy but might clarify the intake a bit better.
The reddish boot with 2 clamps is the throttle body boot. Disconnected, there is strong suction there with the throttle plate open.
Note the aluminum tube runs to the opposite side where it’s connected to the turbocharger by a similar boot. From the turbocharger there is a plastic tube running back to the large ribbed boot with the bulge in it to the left of the coolant tank.
The fuel lines to the right of the bulge run from the fuel dist. to the injectors.
The air sensor plate, which operates the fuel distributor plunger, is at the bottom of the bulged boot. The underneath side of the air sensor plate is routed to the air filter housing and incoming air will raise the plate a certain amount, depending on how far the throttle plate is opened. The vacuum solenoid sits on top of the rad. support.
This model is not exactly like mine but is very very similar.
By warmup regulator I mean the control pressure regulator. CPR is the proper name but most techs I know refer to it as the warmup regulator and it controls fuel pressure from the cold start onwards. The Aux. Air Reg. only provides additional air during engine warmup.
Hope that helps some and I apologize for how disjointed this all is. This car has caused me to become a bit disjointed and when, if ever, the problem is solved I think that I’m going to feel like a card-carrying fool for overlooking something.
School started on the 25th of Aug and after my inital read of your concern I have been busy in IT land (making a Fedora 13 box with free open source software for some students to test). Imagine my suprise when I log on tonight and this question is number 2 on the page. I ask anything to add? Did you look at the tub the pump sits in and what about an accumulator issue? Perhaps these answers are buried in the thresd somewhere but I have seen these cars have accumulator issues.
OK:
In my reply last night, I mistakenly used the word “vacuum” when I meant to use “suction”. Sorry for the confusion.
Your picture and the plumbing explanation helped as it’s been years since I’ve worked on my wife’s VW with a similar system.
If it doesn’t suck so hard at the end of the intake tract where it connects to the fuel distributor boot, is there anyway to determine if there’s an air leak in that plumbing? Could you cap both ends, apply pressure to it, and see if it leaks? I keep coming back to the sensor plate and it seemingly not moving.
I can’t think of how the intake side of the turbo could get an air leak, but I can’t let go of the idea either.